Hossein Roshani

Rutting performance prediction of warm mix asphalt containing reclaimed asphalt pavements

Nowadays, saving energy and recycling materials are becoming priorities in the road construction industry. This paper presents an experimental study to characterise permanent deformation of a warm mix asphalt (WMA) mixture containing reclaimed asphalt pavement (RAP). The WMA mixtures containing 0%, 15%, 30%, 50% and 60% of RAP were plant prepared. To assess the impact of RAP on rutting properties of hot mix asphalt, mixtures were tested using Marshall and dynamic creep tests. It was found that replacing up to 60% of the virgin aggregate with RAP improved rutting properties of the asphalt mixtures because RAP increased asphalt binders viscosity as a main factor of rutting, especially at high temperatures. However, replacement of too much RAP in asphalt mixtures can increase moisture sensitivity of flexible pavements. Therefore, an indirect tensile strength test was conducted to evaluate moisture damage of the mixtures. The results showed that the minimum permissible tensile strength ratio (TSR) of 70% was satisfied by replacing up to 50% of the virgin aggregate by RAP; but the mixtures with 60% RAP had a TSR of less than 70%. Accordingly, 50% replacement of RAP was found to be the optimal replacement level.

Energy Harvesting from Roadways

This paper presents a preview of an ongoing study to develop an energy harvesting system based on piezoelectric elements embedded into the pavements structure. The system development involved designing and testing a number of prototypes in the laboratory under controlled stress conditions. In addition, it involved numerical modeling of the stress distribution in the power generation module and economic analysis of the value of the electric power generated, under a given traffic composition scenario. The results available to date suggest that this technology shows promise in powering LED traffic lights and wireless sensors embedded into pavement structures.

Theoretical and experimental evaluation of two roadway piezoelectric-based energy harvesting prototypes

AbstractThis paper presents the results of a theoretical and experimental study aiming to develop a stress-based roadway energy harvesting system. It describes two prototypes using piezoelectric el...

Experimental and finite element assessment of three energy harvesting prototypes for roadways

The transportation infrastructures serve a critical societal need to rapidly move goods and people across the nation. Using these infrastructures as a source of renewable energy by harvesting them from the roadways is a novel idea that has not been fully explored yet. Highway pavements are exposed to energy-potential resources from vehicle vibrations and traffic loading strains. Energy harvesting is a process that captures unused ambient energy such as heat, vibration, stress or movement that would otherwise be lost. Piezoelectric transducers are considered materials for harvesting energy in pavement structures as they convert mechanical strain into low voltage. For this purpose, two types of piezoelectric geometry were evaluated; cylindrical disks and thin film, suitable for compression and bending state of stresses, respectively. Two prototypes including piezoelectric disks connected in series and parallel were evaluated to study the effect of loading frequency and magnitude on output power under compression. Another prototype containing thin piezoelectric film was developed to investigate the potential of energy harvesting in bending condition. Finite element (FE) analysis was conducted to simulate prototypes’ response under loading. The evaluation of the prototypes involves laboratory testing of their power output as a function of stress and FE simulation of their mechanical behavior. The results showed that the energy harvesting modules should be designed to capture vertical compressive stress in pavement instead of tensile stress. Results suggested that voltage is highly dependent on loading magnitude. It was also concluded that piezoelectric stack connected in parallel produces higher current output under similar loading conditions.

Field Investigation of Relationship between Pavement Surface Texture and Friction

Proper tire–pavement interaction is essential for the safety of motorists. Pavement surface texture is a major contributing factor to tire–pavement friction. This study performed a series of statistical analyses of field-measured friction and texture data to find the texture–friction correlation. Three test sections with different pavement types were selected within the state of Texas. Data were collected at three locations in the right wheel path and three locations in the center of the lane for each test section. To measure the texture data, the researchers used the circular track meter (CTM) and a prototype measurement device developed in-house and consisting of a line laser scanner (LLS). Friction measurements were obtained with the dynamic friction tester (DFT) and Grip-Tester. The mean profile depth (MPD) was calculated by using the measured texture data. The relationship between the MPD values and the friction numbers obtained from the Grip-Tester and DFT was investigated at speeds of 50 and 70 km/h (31.1 and 43.5 mph). The repeatability and reliability of both the developed LLS prototype and the Grip-Tester were also evaluated, as well as the effect of test speed on friction measurement. The results indicated a strong positive correlation between the texture and friction data. In addition, the developed LLS prototype was able to scan the pavement surface texture more reliably and precisely than the CTM in terms of vertical and horizontal resolution. The Grip-Tester showed promising results compared with the DFT with regards to the friction measurement.

Evaluation of a Line Laser Scanner to Improve the Measurement of Average Least Dimension in Chip Seal Design Methods

Chip seal, as the most widespread pavement preventive treatment, is regularly applied on existing pavements that are still in good structural condition to increase the pavement serviceability. The most effective key parameter on chip seal performance is binder application rate, which directly governs chip seal distresses such as bleeding and raveling. How this rate is calculated mainly depends on the value of least dimension (LD) of aggregate particles. However, the available measuring methods of LD value are slow, laborious, and subjective. This study presents the development of a new high-speed line laser scanner (LLS) prototype to measure the LD value of particles more quickly and accurately. The LD values of aggregate particles were also measured using a digital caliper and considered as control data. The repeatability and reliability of the developed LLS prototype were evaluated, as well as the speed of the prototype in calculating the LD values of 100 aggregate particles. The findings indicate that the measurements of the developed prototype are highly correlated with those of the caliper. In addition, it was found that the developed prototype is efficient and capable of calculating the LD values of several particles simultaneously.

Development and Finite Element Analysis of Piezoelectric-Based Prototypes for Harvesting Energy from Roadway Pavement

Energy harvesting is a process that captures unused ambient energy such as heat, vibration, stress or movement that would otherwise be lost. Highway pavements infrastructure exposed to energy-potential resources from vehicle vibrations and traffic loading strains that could be harvested. Piezoelectric transducers (PZT) are potential materials for harvesting energy from pavements as they convert mechanical loading strains into electric voltage. For this purpose, this study is aimed to evaluate two types of piezoelectric prototypes integrated within asphalt mix; cylindrical disks and thin film sheet, suitable for compression and bending state of stresses, respectively. Finite element (FE) analysis was conducted to simulate prototype response in different geometry under dynamic loading. The evaluation of the prototype involves laboratory testing of their power output as a function of stress, and FE simulation of their mechanical behavior. Results suggested that power output is highly dependent on loading frequency and magnitude and PZT geometry but could be promising in powering low-watt LED traffic lights and wireless sensors embedded in pavement particularly in remote areas.